PURPOSE: We aimed to describe computed tomography (CT) findings in patients with peritoneal, omental and mesenteric lymphoma involvement. MATERIALS AND METHODS: We searched our archive retrospectively to find out patients with peritoneal, omental and mesenteric lymphoma involvement. We found 16 patients with non-Hodgkin lymphoma meeting these criteria. CT studies of these patients were reevaluated for the presence of peritoneal involvement, ascites, omental mass, organomegaly, retroperitoneal lymphadenopathy, bowel wall thickening and other associated findings. RESULTS: There were 14 males and 2 females with peritoneal and/or mesenteric and omental lymphoma involvement. Mean age was 39 (range 4-76). Subgroups of non-Hodgkin lymphoma were diffuse large B-cell lymphoma (n=11), small cell lymphocytic lymphoma (n=2), small cleaved cell lymphoma (n=1), T-cell lymphoma (n=1) and Burkitt's lymphoma (n=1). Peritoneal involvement was seen in 15 patients (93.8%) in the form of linear (n=12) and nodular (n=3) thickening. Ascites was seen in 12 (75%) patients. Omental and mesenteric masses were present in 10 (66.6%) and 10 (66.6%) patients, respectively. Bowel wall thickening, retroperitoneal lymphadenopathy and hepatosplenomegaly were also common and observed in 10, 10 and 11 patients, respectively. Solid organ involvement in the form of liver and splenic lesions was seen in 9 (56%) patients. CONCLUSION: Peritoneal involvement can be seen in many subtypes of lymphoma and most frequently in diffuse large B-cell lymphoma. Peritoneal lymphomatosis can mimic peritoneal carcinomatosis and should be included in the differential diagnosis list in patients with ascites, hepatosplenic lesions and unidentified cause of peritoneal thickening on CT in a male patient.